1. Field of the Invention
The present invention relates to a signal processing apparatus and a signal processing method.
2. Description of the Related Art
A communication system that performs non-contact communication of data between a non-contact IC card and a reader writer is used for various purposes such as a settlement terminal of a shop, an entry/departure control terminal of an office, and an automatic ticket examination of transportation facilities. To change such an installed and operated communication system as a whole or to change communication performance of a reader writer, a heavy investment in terms of cost and work load such as a modification or replacement of the reader writer and technical examination thereafter is necessary.
If, for example, the communication distance of a reader writer installed in a shop should be extended or a communication area should be expanded in a horizontal direction, it is necessary to take action of replacing or modifying the reader writer. However, when an existing reader writer is replaced, there are issues of rising replacement costs and the loss of compatibility of the communication interface between the reader writer and a host apparatus. When a reader writer is modified, it is necessary to take an electromagnetic influence caused by an analog circuit inside the reader writer or the environment around the reader writer into consideration, which produces an issue that technical restrictions and items to be examined arise for modification.
Thus, Japanese Patent Application Laid-Open Nos. 2005-323019, 2008-306689, and 2000-138621 propose to arrange a booster antenna including a resonant antenna coil opposite to a reader writer antenna to extend the communication distance of an existing reader writer or to expand a communication area. With Q (Quality factor) of a resonance circuit intensified by resonating a magnetic field between the reader writer and a non-contact IC card by the booster antenna, the communication distance of the reader writer is extended.